Pulse forming circuit



April 6, 1954 5. J. 'KRULIKOSKI, JR, ETAL 2,674,691

PULSE FORMING CIRCUIT Filed Dec. 50, 1949 2 Sheets-Sheet l E E INVENTORS STANLEY J. KRULIKOSKJR.

DANA c. MANNING JOSEPH F CLAYTON #71- TORA/EY April 6, 1954 s. J. KRULIKOSKI, JR., ET AL PULSE 'FORMING CIRCUIT 2 Sheets-Sheet 2 Filed Dec 30, 1 949 VOLTAGE TO ARC-N6 CIRCUW APPLIED .6 .7 RATIO OF FREQUENCY OF RESONANT FREQUENCY OF CH BY J KR DANA BY JOSEPH F. CL

IQTTORNEY Patented Apr. 6, 1954 I NIT-ED ..,:S.TATJE"S PTQFFICE "PULSE' FORMING GIROUIT vS-tanley J.- :Krulikoski, J r.,rD,earborn, and Dana, 10. Manningand Joseph F. Clayton, l-Detroit Michn assignorsr tosBendixeAviation. Corporation, .Detrait; Michma corporation ofD'elaware Application Becember 30, 1949, Serial No. 135,952

r 9rClaims. (Cl. 250-27) This invention relateswtomulseij forming-cir- Otherjobjects and. advantages of,.the invention u'cuits; and moreparticularly'toipulse forming cirwillbe apparent, ,from a detailed description .of zcuitsrsproviding ta maximum amountuofgpnwer iithetinventionand vfrom the appe ed drawil lgs :and.:stability. and claims.

In wline pnlsewforming circuits v ;:using,.; ,i1 H l'gIn the drawi 1" ductance charging from asourcesofgalternating Figure 1I,,is.a,.schematic dia ram of a pulse xavoltage, :a ipower supplyt vchargesnv'ior-;a.=predet. formin circuit; :ztermined. period .of;:time, arinetwo-rkthaving; a t -Fi re} illustratesrwaveforms of the volta e mcapacitive' sreactancerat. the. chargingjrequency. .and.current.at variousfioin s in he pu1seform- "Thezanetwork-is partrfof a series resonantgcircuit .;ioe' ircuit shown, in F 1;

so; thatait is"charg.ed-. '.tos a'relatively high voltage I'F 3 i a r ph. sh win t e maximum :iduring the "chargingiperiod whiehma voltage to which the condenser ,is, charged when :rone or morecycles. "Atlthe end. of :the' charging "the frequ n y of the, p lied voltaee'varies with ;1peri0d;-.a switch ;is closedtopermit theunetwork v fii ect torthe re on r qu cy of the, chargto discharge through a load, producingvaupulse 5s n i itk n across-:the'load. i The charge and discharge of Tl iure 4 isa, schematic dia m f a circuit ,;.the;netwo-rkaare.repeatedat:predetermined;iinl' u a ine another e bodiment of the inventervals .to, provide; pulses having, a; definite; re- .tion.

, petition".frequency. The .pulsesare utilized. 'in In'the embodiment the v nvshown, in imany types of radar systemsrtoito btain thegdi- F e a t at n voltage is app d y a rectionaandprange of a;distant object. enerator It to a transformer H. "The trans- To tclosext'he switch,: previouszcircuitshave-zrelifurmelhas'one Side of its Secondary Winding 2 .liedvon a:specific phase irelationshipyhetweenthe r-connefited i primary Wind n 14 a f applied Voltage ndth tlt 1; entiating transformer l6, and the other side of Any changesrinathefrequency of the appliedvoltz5=- 'secQndarry Winding is connected ou rage causethisxphaserelationship touvary. a chal'gingi inductance e plate of t ;wresulnuchanges :in the vfrequency of thevapplied 'i fi, SflCh'aS y fillbevoltage. .preventtthe; network fromcdischargingsat e' m ry i n andisecondary Winding t t t t t t been :gha rged;tu a maxi -19 of the transformer l6 are connected together 1 mum value, 3 .at one side and grounded. The other-side of the This invention-employs .a';fixeduphasemela- Winding 19 Connected through a tionship between-the chargingcurrenthandathe T'blocking condenser i e d of a tube 22- "voltage on the-network torprovidea pulse-whose erid leak resistance 23 is provided between ;rcharacteristicsxare substantiallyrindependent;of i negative terminal of a battery '.the frequency: of the applied; voltage. I '25,11the positive terminalof which is grounded.

An object of;this;.invention is .toaprovide. arch The cathode of the tub? is also groundedcuit for producing a pulse ofpmaximumzstability wTheplates-of'the tubeqz and of second tube regardless'of any changeszinathefirequencynozf the 724 are-connected by a lead grid the zapplied voltage ;tube24. is connected'through a grid leak .re-

Another object is to providga -cir it of the sistance' 28 tothe negative terminal of a battery :nabove character :for aproducingarpulseof @maxi- "729bthe positive terminal of which s groundfid, ::.mum: amplitude even gthough :thexgfrequency; of and'the cathode of'the tube 1534150 u dvthe appliedusienal may vary. .'The resistance28, and battery 29 are in parallel 'A further'objectwis-to'provide-asynchronizin with a branch which has condenser 30 in *pulse'lforming' circuitlhavinga' x d :phase 1 ..ries .with a secondary winding 32 of a transtionship between cthe charging. current tfandgthe tf r e a1ly indicated primary -.vo1tage on-the network. ."wincling36.'0f the transformer 34 is connected stillnanotherrobjecttis. toprovide..a.:.ciroult; or eenEthe. plateof'the tube 24 and the, positive the above character which. wi11:;-require :aLminit.erminal-of a plate supply, such as the battery .zrmum :number. of parts and .occupytacrminimum 5 31. thevne ative.terminalnof which .is grounded. @flkmmlnt p c era-secondary winding. is connectedbetween. the

A'=:sti1l2.further :object of lthe. :inventiontisa to r t m "provide a' circuit of'nthe 'a'boveacharaoteruwhich Plate -=vo1ta nf0n the-tube 42 .is, supplied will-iibe efl'icientrand.reliable @inaopenatiommnder hrou htauleadwflzl-iroznrthe; battery: 37 T all conditions. wtcathodesrofnthe LtIZbBREiSHGOIIHBCtBdI tong-round through a resistance 46 and a by-pass condenser 48 in parallel with the resistance. The cathode is also connected through a blocking condenser 50 to the grid of the hydrogen thyratron tube I8. A resistance 52 is provided between the grid of the tube I8 and ground, and the cathode is grounded. In addition to being connected through the inductance H to the secondary winding I2 of the transformer III, the plate of tube I8 is connected in series with a pulse forming network, generally indicated at 54, having a plurality of sections of inductances and capacitances, with the capacitance of each section having a value of C. With 11. sections, the network has a capacitive reactance of approximately at the frequency of the applied voltage where we is the angular frequency of the applied voltage. The network 54 is connected to the primary winding 53 of a pulse transformer 65 and the other end of the primary winding is grounded.

The inductance of the differentiating transformer It is low for large currents. As is Well known, the voltage induced in a transformer as current flows through it is proportional to Ldi/dt, where L is the inductance and di/dt is the rate of change of current. When a current having a waveform resembling a sine wave flows through the transformer I5, both L and di/dt have high values as the current passes through zero and low values as the current approaches a positive or negative peak. As a result, the voltage induced in the transformer has a positive pip when the current is passing through zero in a positive direction and a negative pip when the current is passing through zero in a negative direction.

The positive voltage pip produced by the transgether, the drop in plate voltage on the tube 22 produces a corresponding drop in the plate voltage on the tube 24 and therefore an increase in voltage across the winding 36. This causes a voltage pulse to be induced in the winding 32 and this pulse is applied to the grid of the tube 24, causing the current through the tube to increase and the plate voltage to drop even further. As a result, the voltage pulse across the winding 35 is amplified by the regenerative action of the tube 24 and the transformer 34.

The voltage pulse in the winding 35 is induced in the winding 45] and introduced to the grid of the tube 42. This causes the current through the tube to increase and produces a trigger pulse across the resistance 45. This pulse is applied to the grid of the hydrogen thyratron tube I8. The tube I3 is normally cut off but the trigger pulse from the resistance 46 causes the tube to break down and conduct.

The current flowing through the differentiating transformer I6 also flows through a circuit which includes the secondary winding I2 of the transformer II, the inductance II, the network 54 and primary winding 58 of the transformer 60. This circuit is series resonant, thereby causing a large amount of energy to be stored in the network 54 during each cycle of applied voltage. Since the network is capacitive at the frequency of the applied voltage, the current which flows through the resonant circuit to charge the net- 4 Work 54 leads the voltage on the network by 90. As previously stated, the hydrogen thyratron tube It is triggered and conducts when the current through the transformer I6 is zero. Because of the 90 phase difference, the network 5 5 is charged to a maximum voltage at this instant. When the tube I8 conducts, the network discharges through a circuit which includes the network, the tube I8 and the primary winding 58 of the pulse transformer 68. The discharge of the network produces a pulse of short duration and of an amplitude determined by th energy stored in the network.

As discussed above, both the formation of the voltage pip in the differentiating transformer I5 and the maximum charging of the network 54 occur when the current in the charging circuit is zero. Therefore, the network 54 will discharge at a voltage maximum whether or not there is any variation in the frequency of the signal applied to the transformer I I.

These relationships are illustrated by the curves shown in Figure 2. Curve 64 shows the charging current through the transformer I6 and the network 54. The voltage pips produced by the transformer I5 are shown in curve 66, and the voltage on the network 54 is shown in curve 58. As may be seen, the positive pips shown in curve 65 coincide in phase with the maximum voltages en the network. Curve 10 shows the shape and phase of the pulses produced across the pulse transformer by the discharge of the network 54. In curve 12, one of the pulses is enlarged to illustrate its shape more I clearly.

Figure 3 is a graph which shows the maximum voltage to which the network 54 is charged when the ratio between the frequency of the applied signal and the resonant frequency of the tuning circuit varies. As may be seen, the optimum voltage which can be obtained on the network occurs when the applied frequency is approximately 70% of the frequency to which the charging circuit is tuned. If the applied frequency is taken at approximately of the tuned frequency of the charging circuit, a negative drift in the frequency of the applied signal will cause the maximum voltage on the network to increase slightly and a positive drift will cause the maximum network voltage to decrease slightly. However, the maximum network voltage will be substantially constant for the frequency range of the applied signal which will normally be encountered. This causes the amplitude of the pulses formed across winding 58 to be substantially constant under normal operating conditions.

In Figure 4, a circuit is shown for producing pulses during alternate cycles of applied voltage. In this circuit, the secondary winding I06 of a transformer I04 is connected between the primary winding I08 of a differentiating transformer H0 and a charging inductance I I I, which is connected to the plate of a hydrogen thyratron tube I I2. The winding I 08 is also connected to one side of the secondary winding H4, which is grounded. The other side of the secondary winding is connected through a resistance II6 to the grid of a tube I I8.

The cathode of the tube H8 is grounded and a positive voltage is applied to the plate through a resistance I20, the voltage being supplied from a suitable source, such as a battery I22. The

plate is also connected through a capacitance I24 to the grid of a second tube I26.

tive reactance at the frequency of the alternating voltage, a load, an inductance connected in series with the voltage source, the network and the load to provide a voltage pip at substantially zero current therethrough, a normally non-conductive gas-filled tube connected across the network and load, and means associated with the inductance and the gas-filled tube for converting the voltage pips into triggering signals to provide conduction through the tube for the resultant discharge of the network.

4. A pulse forming circuit, including, a source of alternating voltage, a network having a capacitive reactance connected to the voltage source, adifierentiating transformer connected in series with the network and the voltage source to produce a voltage pip for substantially maximum voltages on the network, and a normally open switch connected to the network and adapted to be closed upon the formation of voltage pips to provide a discharge path for the network.

5. A pulse forming circuit, including, a source of alternating voltage, a network, a load, magnetically operative means forming a series circuit with the voltage source, the network and the load to provide a voltage pip at substantially zero current therethrough, a normally open switch connected across the network and load, and means connected between the magnetic means and the switch for converting the voltage I;

the difierentiating reactance and the load, connected in series to form a resonant charging circuit for charging the network to a maximum value when the current through it is substantially zero, and a normally open switch controlled by triggering pulses from the reactance and connected to the network and the load to provide a path for the discharge of the network through the load upon the formation of the triggering pulses.

I. A pulse forming circuit, including, a source of alternating voltage, a network adapted to be charged by the voltage source, magnetically operative means adapted to produce a triggering pulse upon the flow of substantially zero current through it, a load, means, including the voltage source, the network, the load and the magnetically operative means, connected in series to form a circuit resonant at substantially the frequency of the alternating voltage, and a normally open switch connected to the network and the load and operative upon a triggering pulse from the magnetically operative means to provide a discharge path for the network through the load.

8. A pulse forming circuit, including, a source of alternating voltage, a network adapted to be charged by the voltage source, an inductance adapted to produce a triggering pulse for substantially zero currents through it, a load, means, including the voltage source, the network, the inductance and the load, connected in series to form a circuit resonant at substantially the frequency of the alternating voltage, and a gas-filled tube having a cathode, a grid and a plate, the grid of the tube being connected to the inductance to receive the triggering pulses and the cathode and plate of the tube being connected between the network and the load to provide a path for discharging the network through the load upon the introduction of the triggering pulses to the grid.

9. A pulse forming circuit, including, a source of alternating voltage, a network adapted to be charged by the voltage source, a differentiating reactance adapted to produce a triggering pulse for substantially zero currents through it, a load, means, including the voltage source, the network, the differentiating reactance and the load, connected in series to form a circuit resonant at substantially the frequency of the alternating voltage, and a normally cut-off gas-filled tube having a cathode, a grid and a plate, the grid of the tube being connected to the difierentiating reactance and being biased to produce a conduction of the tube upon the introduction of the triggering pulses, and the plate and cathode of the tube being connected to the network and the load to provide a path for discharging the network through the load upon the conduction of the tube.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,405,069 Tonks July 30, 1946 2,409,897 Rado Oct. 22, 1946 2,429,471 Lord Oct. 21, 1947 2,444,782 Lord July 6, 1948 2,577,512 Cooper et al Dec. 4, 1951 

